Arc protecting device with c-shaped horns for suspension insulators



Jan. 12, 1965 J H MEIER 3,165,577

ARC PROTECTING [BEVICE WITH C-SHAPED HORNS FOR SUSPENSION INSULATORS Filed March 21, 1963 INVENTOR.

Jaw HEN/P/ Nave- BY f United States Patent s 165 577 ARC PROTECTING bnvrcn WITH C-SHAPED HORNS FOR SUSPENSION INSULATORS Jean Henri Meier, Tarbes, Hautes-Pyrenees, France, as-

4 Claims. (a. 174-141 The present invention relates to a horn device for the protection of insulators against electric arcs, which is adapted to ensure easier blowing out of flashover and to protect certain delicate parts from the latter.

The device according to the invention comprises essentiallymetallic horns, the shape of which is that of an open concave curve corresponding roughly to the shape of the letter C, with more or less elongated arms. This horn is disposed in a plane extending through the longitudinal axis of the insulator, the opening of the C facing outwards. The horn is connected by a metal shank to the bracket by which the insulator is suspended or secured.

The present invention appears to offer greater interest when employed with brackets of the type which are to be internally sealed at the ends of the stem of helical-finned suspension insulators.

The description which follows with reference to the accompanying drawings, which are given by way of nonlimiting example, will enable the manner in which the invention can be put into practice to be readily understood, the features appearing both from the text and from the drawings naturally forming part of the said invention.

FIGURE 1 is a diagrammatic elevational view of a string of two insulators provided with arcing horns according to the present invention,

FIGURE 2 is a fragmentary view in perspective thereof.

The arcing horns according to the present invention comprise C-shaped free ends 1 fast with a metal shank or pin 2 by which they are connected to a bracket 3 by which the insulator 4 is suspended or secured. In the example illustrated in the drawing, the insulator is of the helical-finned type having a solid insulating stem.

It will be noted that the C-shaped ends of the horns open outwards and that they are situated substantially in planes extending through the longitudinal axis of the insulator.

It will also be noted that the longitudinal dimensions and the positioning of the horns are so chosen that they do not project over the ceramic of the insulating stems, in order not to reduce the arcing distance, which depends upon the length of the apparent ceramic. More precisely, the horns have a maximum height substantially equal to the distance separating the apparent ceramic of successive elements of a string of insulators. Consequently, no reduction of the insulating properties of the insulators is produced by the introduction of the protective device into the string, the arcing distance measured over two protective devices disposed on either side of an insulator being substantially equal to the arcing distance measured over the insulator.

In the event of flashover due to arcs jumping between the brackets, as a result of the particular shape of the horns, of which the ends 12 and 13 converge, the points at which the upper and lower arcs impinge upon the protective horns disposed between the two insulators 44 tend to move towards one another and to merge as a result of electromagnetic action, while moving away from the axis of the insulator, thereby facilitating the junction of the two arcs to form a single are which is easier to blow out.

In the constructional form of FIG. 1, the protection of Ice the ends of the insulator string is completed by shunts directly connecting the horns to the line 5 or to the pylon 6 througha clip 7, straps 8 and clips 9 and 10. 'Thus, the suspension members between the insulator and the pylon and between the insulator and the suspension clip 11 are protected from the destructive effect of the arc.

Although it is not essential to employ for devices for protecting the ends of the strings horns having the same form as those in the device employed for the protection between successive insulators, it is advantageous to do so, because it is desirable, in order to standardize the equipment required, to use the same form of device at all levels of the string especially when, as in the present case, the protective device which is integrally formed with the sealing fitting is incorporated in the insulator. In addition, the C-shape of the horns provides a zone over which the clip 7 is secured and which is always protected from the destructive action of the seat of the arc.

Each protective device according to the invention will comprise at least one C-shaped horn, but preferably three or four.

If there is an even number of horns, for example four, these horns may be formed of pairs of elements at to one another, as illustrated in FIGURE 2.

Two of these pairs are then secured to the suspension bracket 3 by means of a bolt 14.

If the number of horns is small, for example three, the

horns may be integrally cast withthe suspension brackets,

by reason of the reduced dimensions of the parts of the protective device.

It is'also possible to modify the length of the shanks 2 and consequently to bring the flashover are further away from or closer to the string of insulators. However, the horns cannot be disposed too far from the axis of the insulator without danger of a portion of the are travelling, for example, along the right-hand horn, While the other portion might travel along the left-hand horn so that the arc might brush past the junction members. It seems that a distance between the opposed horns of the order of 1 to 1.5 times the diameter measured on the fin of the insulators is the most appropriate.

The device according to the invention may be applied to any suspension insulator or string of suspension insulators, but it affords the greatest advantage when applied to internally sealed insulators, notably those of the Spirelec type. Spiralec is United States Trademark No. 759,566, granted November 5, 1963 to Compagnie Gnrale dElectro Cramique for insulators and insulating devices and more specifically for insulators of the type patented in United States Patent Nos. 3,110,759 and 3,110,760.

A string of internally sealed insulators has among other advantages, as compared with a string of insulators having an externally sealed bracket, that of a reduced length for a given insulation, as also a minimum distance between the apparent ceramic of two contiguous insulators. Now, as has been seen in the foregoing, the dimensions of the protective device according to the invention are determined by the distance, and they will therefore have small dimensions and can consequently be very readily mounted on the brackets 3 or even be integrally formed therewith, without the shape or size of the said bracket having to be modified to receive the protective device. As used herein, the term internally sealed as applied to insulators refers to insulators which utilize metal fittings which are cemented in a cavity in the end of the insulator body whereas the term externally sealed as applied to insulators refers to insulators which utilize metal fittings which are cemented to an external portion of the end of the insulator body.

It will be obvious that modifications may be made to the embodiment hereinbefore described, notably by substitu'tion of equivalent technical means, without departing from the scope of the present invention.

I claim:

1. A suspension insulator comprising a generally cylindrical body of insulating material, said cylindrical body having at least one blind bore at an end thereof, a pair of metal fittings, at least one of said fittings having a portion Which-iscemented within said blind bore in an 'endof said cylindrical body, said metal fitting having a portion sealed within said bore of said body having at protecting device against electric arcs, said protecting device having atleast one horn having a generally C-shaped free end portion, said free end portion-'opening-in a direc- 'tion away from the longitudinal axis of said metal fitting,

the longitudinal extremity'of said C-shaped free end portionnearest saidendof said cylindrical body not extending beyond-a transverse plane passing through the end of said-cylindrical body.

2. A'suspension insulatorcomprising a generally cylindrical body of insulating material, said cylindrical body having blind bores at the ends thereof, a pair of metal fittings, one of said metal fittings having a portion which is cemented 'Within said blind bore atone end of said body and the other of said fittings having a-portion which is cemented within said blind bore at the other end of "said body, each-of said metal fittings being provided with a protecting device against electric arcs, each of said protecting devices having "at least one arcing horn having a generally C=shaped "freeend portion, said freeend portion opening away from the longitudinal axis of said metal fitting and being disposed in a longitudinal plane passing through said-cylindrical body, the narrowest interval between the arcing hornsofthe-opposite metal fittings being at least equal to the length of said cylindrical "body.

.3. The suspension insulator of claim} wherein said cylindrical body is provided with a spiral flange extending from one end of said body to the other thereof.

4. A suspension insulator assembly comprising at least one insulator having a generally cylindrical body of ceramic material, said cylindrical .body being provided with blind 'bores at the ends thereof and having a spiral flange extending form one end of said body-to the other end thereof, said insulator being provided with apair of metal fittings, one ofsaid metal "fittings having a portion which is cemented within said blind hole at one end of said body and 'the other of said fittings having a portion which is cemented within said blind bore at the other end of said body, each of said metal fittings being provided with a protecting device against electric arcs, each of said protecting devices having a plurality of arcing .horns, each of said horns having a generally .C-shaped free end portion, said free end portion opening away from the longitudinal axis of said metal fitting, the height of said C-shaped free end portion being no greater than the disstance between the freeinsulating surface of two superposed insulators.

References Citedby the Examiner 'UNITED STATES PATENTS 3,110,758 11/63 Meier 174-179 X FOREIGN PATENTS 108,033 '7/ 43 Sweden. 723, 348 8/ 42 Germany. 917,116 1/63 Great .Britain.

JOHN F. BURNS, Primary Examiner.

JOHN -P. WILDMAN, Examiner. 

1. A SUSPENSION INSULATOR COMPRISING A GENERALLY CYLINDRICAL BODY OF INSULATING MATERIAL, SAID CYLINDRICAL BODY HAVING AT LEAST ONE BLIND BORE AT AN END THEREOF, A PAIR OF METAL FITTINGS, AT LEAST ONE OF SAID FITTINGS HAVING A PORTION WHICH IS CEMENTED WITHIN SAID BLIND BORE IN AN END OF SAID CYLINDRICAL BODY, SAID METAL FITTING HAVING A PORTION SEALED WITHIN SAID BORE OF SAID BODY HAVING A PROTECTING DEVICE AGAINST ELECTRIC ARCS, SAID PROTECTING DEVICE HAVING AT LEAST ONE HORN HAVING A GENERALLY C-SHAPED FREE END PORTION, SAID FREE END PORTION OPENING IN A DIRECTION AWAY FROM THE LONGITUDINAL AXIS OF SAID METAL FITTING, THE LONGITUDINAL EXTREMITY OF SAID C-SHAPED FREE END PORTION NEAREST SAID END OF SAID CYLINDRICAL BODY NOT EXTENDING BEYOND A TRANSVERSE PLANE PASSING THROUGH THE END OF SAID CYLINDRICAL BODY. 